The blood of the physiologically healthy man and animal, contains more than 50% insoluble components, mainly in the form of plasma cells. These components of blood flow at high speed through capillaries having a diameter less than 5.mu., in spite of the fact the diameter of plasma cells such as erythrocytes or leucocytes is 5-10.mu. and sometimes larger than the capillaries. Consequently, to attain smooth passage of blood through the small capillary, distension of the capillary wall as well as deformation of the plasma cells is substantially required. The present inventors have indicated that friction between plasma cells and the vessel wall is an important factor in maintaining blood flow in microcirculation. Various pathological conditions or diseases may result from or be aggravated by lack of lubrication of the cells, namely peripheral thrombosis, phlebo-thrombosis, cerebral thrombosis, ischemic heart disease, plasma cell sludging, disseminated intravascular coagulation, other microcirculatory failures, platelets agglutination or bleeding caused by excessive hemolysis in cancer patients under treatment with antitumore agents. Furthermore, in devices for assisting extracorporeal circulation fine tubings with poor lubrication and distensibility result in frequent troubles due to accompanying hemolysis even after their use for a short period of time.
The inventors have been engaged for a long period of time in investigating methods or treatments of preventing damage to blood cells during the passage of the cells through the capillary which may lead to the alleviation of the pathological conditions associated with the previously mentioned diseases. The inventors have already filed patent applications on a process of producing stable protein solutions (Japanese Pat. Appln. Laid-open No. 37,187/'78) and substances for improvement of peripheral circulation using a glycoprotein (Japanese Pat. Appln. Laid-open No. 15,213/'81).